My first introduction to RDS was well before I had an RDS capable radio, as a trainee broadcast technician many years ago I once go a call from AusNav to reset a modem connected to their DGPS box, this was used before the average GPS user was able to get an accuracy of within a meter (no longer the case). Users such as farmers had to subscribe to this service which essentially provided them repeated GPS information from a static base station, therefore providing a more accurate position.
After tracing the cables and reading a few manuals I found out that this service was ingested into an auxiliary port of the Triple J 20KW transmitter that serviced my area, most likely they paid the the NTA (National Transmission Agency, now owned by Broadcast Australia) an ongoing fee for this. I didn't think too much of this again until I bought a new Dennon Amp /Receiver and on tuning in Triple J some text appeared on the display "TRIPLE J - USE DAILY BUT IF PAIN PERSISTS CONSULT YOUR DOCTOR".
Later the following year I had a trip to the UK where the car I hired had an RDS receiver in it, so played about with some features, in many European counties these features are used widely, with the TA (Traffic Announcements) interrupting normal broadcast when the feature was enabled, and also the auto switching between transmitting towers when a new tower came into range based on an alterative frequency list transmitted with the data. Sadly the tale up in Australia was slow, with very few feature in use. It is largely used here now only for transmitting traffic ancillary data to GPS devices. Also there were only a small percentage of FM receivers in the market that could decode and sue this information.
Many of these feature have been included in digital radio, so no doubt most people won't come across them until they end up at some stage getting a digital radio, but even this has a bit of a slow take up with ver few car manufactures installing this capability by default.
https://www.sutcliffetech.com.au/rdsstations.html